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Clarify data frame limitations in KISS modem documentation.

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ViezeVingertjes
2026-02-06 12:36:13 +01:00
parent 02ddc05c30
commit 1af013c741
1 changed files with 2 additions and 1 deletions
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docs/kiss_modem_protocol.md
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@@ -56,7 +56,7 @@ Maximum unescaped frame size: 512 bytes.
|------|-------|------|-------------| |------|-------|------|-------------|
| Data | `0x00` | Raw packet | Received packet from radio | | Data | `0x00` | Raw packet | Received packet from radio |
Data frames carry raw packet data only, with no metadata prepended. Data frames carry raw packet data only, with no metadata prepended. The Data command payload is limited to 255 bytes to match the MeshCore maximum transmission unit (MAX_TRANS_UNIT); frames larger than 255 bytes are silently dropped. The KISS specification recommends at least 1024 bytes for general-purpose TNCs; this modem is intended for MeshCore packets only, whose protocol MTU is 255 bytes.
### CSMA Behavior ### CSMA Behavior
@@ -268,6 +268,7 @@ Data returned in CayenneLPP format. See [CayenneLPP documentation](https://docs.
## Notes ## Notes
- Data payload limit (255 bytes) matches MeshCore MAX_TRANS_UNIT; no change needed for KISS “1024+ recommended” (that applies to general TNCs, not MeshCore)
- Modem generates identity on first boot (stored in flash) - Modem generates identity on first boot (stored in flash)
- All multi-byte values are little-endian unless stated otherwise - All multi-byte values are little-endian unless stated otherwise
- SNR values in RxMeta are multiplied by 4 for 0.25 dB precision - SNR values in RxMeta are multiplied by 4 for 0.25 dB precision